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Science Forum Index » Physics - Research Forum » standing waves in a superconductor
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| verdigris |
 Posted: Sun Mar 04, 2007 1:34 am |
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Increasing the pressure increases the temperature at which materials
can be type 2 superconductors. Could standing sound waves, passed
through a superconductor, raise the temperature at which it
superconducts, if the troughs of the waves coincide with the
insulating layers and the peaks with the conducting layers -
increasing the pressure in the conducting layers relative to the
insulating layers? The thinking behind this is that in type 2
superconductors it is known that some electrons tunnel through the
insulating layers and help superconductivity - would a sound wave
trough lower the density of the insulating layer and increase the
number of tunneling electrons? |
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| Uncle Al |
| Posted: Sun Mar 04, 2007 9:06 am |
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verdigris wrote:
Quote:
Increasing the pressure increases the temperature at which materials
can be type 2 superconductors. Could standing sound waves, passed
through a superconductor, raise the temperature at which it
superconducts, if the troughs of the waves coincide with the
insulating layers and the peaks with the conducting layers -
increasing the pressure in the conducting layers relative to the
insulating layers? The thinking behind this is that in type 2
superconductors it is known that some electrons tunnel through the
insulating layers and help superconductivity - would a sound wave
trough lower the density of the insulating layer and increase the
number of tunneling electrons?
It's gnerally easier to use larger ions to compress the crystal
lattice and control oxidation state to control band structure.
Pumping energy into a supercon with cyclic energy loss (e.g., internal
friction) works against your goals - the temp rises at cryogenic temps
where specific heat is depressed.
--
Uncle Al
http://www.mazepath.com/uncleal/
(Toxic URL! Unsafe for children and most mammals)
http://www.mazepath.com/uncleal/lajos.htm#a2 |
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| Igor Khavkine |
| Posted: Sun Mar 04, 2007 9:06 am |
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On 2007-03-04, verdigris <waltercress@aol.com> wrote:
Quote: Increasing the pressure increases the temperature at which materials
can be type 2 superconductors. Could standing sound waves, passed
through a superconductor, raise the temperature at which it
superconducts, if the troughs of the waves coincide with the
insulating layers and the peaks with the conducting layers -
increasing the pressure in the conducting layers relative to the
insulating layers? The thinking behind this is that in type 2
superconductors it is known that some electrons tunnel through the
insulating layers and help superconductivity - would a sound wave
trough lower the density of the insulating layer and increase the
number of tunneling electrons?
The pressures necessary to modify the bulk superconducting properties of
a material are huge. They are right up there with pressures necessary to
induce structural phase transitions. That's well beyond the small
amplitude lattice vibration approximation that gives rise to phonons.
Sure phonons are important in considering the physics of a
superconductor (after all they are what provides the binding force in
Cooper pairs), however effect is best described perturbatively in terms
of scattering between electronic and lattice excitations.
On the other hand, you might be interested in optical lattice
experiments (Google for "optical lattice"). There, standing EM waves
generated by laser beam interference patter trap atoms or ions and
effectively control the interactions between them. These techniques have
in recent years allowed experimentalists to build physical realizations
of the simple lattice models that condensed matter theorists have been
playing with for decades.
Hope this helps.
Igor |
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| verdigris |
| Posted: Mon Mar 05, 2007 5:38 am |
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On 4 Mar, 19:06, Igor Khavkine <igor...@gmail.com> wrote:
Quote: On 2007-03-04, verdigris <waltercr...@aol.com> wrote:
On the other hand, you might be interested in optical lattice
experiments (Google for "optical lattice"). There, standing EM waves
generated by laser beam interference patter trap atoms or ions and
effectively control the interactions between them. These techniques have
in recent years allowed experimentalists to build physical realizations
of the simple lattice models that condensed matter theorists have been
playing with for decades.
Hope this helps.
Igor
It would be nice to see an optical lattice with buckyballs in it ( 60
carbon atoms per molecule) - if that is possible. There has been
speculation as to whether the superconductivity of buckyballs is
caused by phonons in individual buckyballs or by all the buckyballs
together. |
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| Dirk Bruere at NeoPax |
| Posted: Tue Mar 06, 2007 3:48 am |
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Guest
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verdigris wrote:
Quote: Increasing the pressure increases the temperature at which materials
can be type 2 superconductors. Could standing sound waves, passed
through a superconductor, raise the temperature at which it
superconducts, if the troughs of the waves coincide with the
insulating layers and the peaks with the conducting layers -
increasing the pressure in the conducting layers relative to the
insulating layers? The thinking behind this is that in type 2
superconductors it is known that some electrons tunnel through the
insulating layers and help superconductivity - would a sound wave
trough lower the density of the insulating layer and increase the
number of tunneling electrons?
Maybe.
However, applying an external pressure is a lot more structurally safe
than applying an internal one. I would guess a lot depends on its
elasticity and strength.
--
Dirk
http://www.onetribe.me.uk - The UK's only occult talk show
Presented by Dirk Bruere and Marc Power on ResonanceFM 104.4
http://www.resonancefm.com |
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